High pressure die casting (HPDC) is a high-volume manufacturing process in which molten aluminium alloy is injected into a hardened steel die at high velocity and high pressure — typically 70 to 140 MPa (10,000 to 20,000 psi) — and held under pressure until solidification is complete. The process produces thin-walled, complex, net-shape components at cycle times measured in tens of seconds. It is the dominant casting process for high-volume aluminium components in automotive, electronics, lighting, telecoms and consumer goods.
Aluminium HPDC is performed on cold-chamber machines, where the molten metal is ladled into a shot sleeve and injected by a hydraulic plunger. Zinc and smaller magnesium parts use hot-chamber machines, where the injection mechanism sits in the molten metal bath.
We supply both processes. They are not interchangeable, and the right choice depends on volume, geometry and end-use requirements.
| Process | HPDC — high velocity, high pressure injection |
| Wall thickness | 1.0–4.0 mm typical, down to 0.8 mm on small features |
| Cycle time | Typically 30–90 seconds — economic at high volumes only |
| Tooling cost | High — justified at volumes of tens of thousands of parts per year and above |
| Surface finish | Excellent as-cast (Ra 1.6–3.2 µm), suitable for paint, powder coat, anodise |
| Internal soundness | Dense outer skin, residual gas/shrinkage porosity in section centres — not suitable for PED pressure-bearing applications or heavy machining of internal features |
| Typical alloys | A380, 383, A360, ADC12, LM24 |
If your component carries pressure or requires PED 2014/68/EU conformity, gravity die casting is the correct process. See our PED-certified aluminium gravity die castings → for that scope of work.
The major HPDC alloy families are AlSi8Cu3 and AlSi9Cu3 type alloys, alongside lower-copper variants for improved corrosion resistance. We routinely supply:
Other HPDC alloys can be sourced to specification. Full chemical and mechanical certification is supplied with every batch, issued against EN 1706, ASTM B85 or equivalent as required.
| Single-piece weight | Few grams up to approximately 5 kg in standard production; larger possible on dedicated machines — discuss at quotation |
| Linear tolerance (as-cast) | Approximately ±0.1 mm on small features, growing with size; tighter tolerances available on critical features by agreement |
| Wall thickness | 1.0–4.0 mm typical; 0.8 mm minimum on small features |
| Draft | 1–2° on external walls, 2–3° on internal walls and cored holes |
| Surface finish | Ra 1.6–3.2 µm as-cast, suitable for paint, powder coat or anodise without further preparation |
| Cored holes | Cast as standard to reduce or eliminate drilling |
| Threads | External threads can be cast; internal threads tapped after casting |
| Inserts | Steel inserts, bushings and threaded inserts can be cast in place |
HPDC components have a dense, fine-grained outer skin approximately 0.4–0.5 mm thick with mechanical properties significantly higher than the centre of the section. Beneath the skin, residual gas porosity from die filling and solidification shrinkage is normal and acceptable for the vast majority of HPDC applications. This has two practical consequences:
HPDC favours specific design choices that reduce defects and tooling cost:
We will review your drawing at the quotation stage and recommend changes that reduce cost and improve castability before tooling is cut.
Every HPDC production order is produced to a defined quality plan. Standard capabilities include:
HPDC components are not supplied under PED 2014/68/EU. If your part falls within the Pressure Equipment Directive, please see our PED-certified gravity die castings →.
Send us a drawing, target volume and alloy specification and we will return a budgetary quotation within three working days.
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